Well, I don't remember much about this from so long ago, but there is a diagram on page 22 of the A701a service manual, and I have a photograph that I took of the switch itself. I can't remember where I found the manual or whether a link was posted in another thread. The manual is dated December 1976 and I haven't noticed a copyright notice. I doubt that it is still (or ever was) incopyright. Try duckduckgo on "A701a service info".
Not sure what you mean by calibration unless you are refeering to the two adjustment screws. I think that too has been covered in other threads.